When you added facts to your person nodes, you set tooltips on these facts. These tooltips will appear in the final application. Therefore, you need to be in Preview mode to see the tooltips.

By default, in the Designer you are in Style Editing mode. In Style Editing mode, you can define style rules as you have been doing.

To switch to Preview mode:

Preview mode shows you the diagram as it will be in an application. This mode allows you to test the application behavior.